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> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Carlsbad will use about thirty per cent more energy
by alwaysdoit 11y ago
> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Carlsbad will use about thirty per cent more energy, five thousand kilowatts per acre-foot, to desalinate ocean water and deliver it to households, according to Poseidon’s report to the Department of Water Resources
These units are abominations. Couldn't just say 2.8 Watts per liter vs 4.0 Watts per liter? Or even 10.6 and 15.3 Watts per gallon? I'm not a metric purist, but the only advantage to using imperial units is that they are more familiar to the average American, but when does the average person deal with acre-feet?
- msandford 11y agoIt doesn't even make sense! The units don't match up. Kilowatts are a measure of power, energy over time, and an acre-foot is a measure of volume, not flow (volume over time). It's like saying how many horsepower it takes to drive from SF to LA. Makes no sense.
- oaktowner 11y agoYes, they must have meant kilowatt hours. Was there no editor?
- istorical 11y agoScientific mistakes in a paper like the new yorker is like poor grammar in a startup CEO's writing. It just happens.
- benkuykendall 11y agoHuh. So they are really talking about a pressure. 1 kWh/(acre ft) = 2919 Pa It makes a great deal of intuitive sense that the quantity that describes how hard it is to move water over a path is a pressure.
- seanflyon 11y agoIt's sad that they mistook kilowatts for kilowatt-hours, but I think acre-foot is a good unit for measuring volumes of water. It helps communicate the scale of water use.
- dredmorbius 11y agoDepends, though I suspect you're right. But expressing energy requirements as power per unit can be quite useful. As in, kW per person or square meter. Though in that case you'd be expressing water delivery as a rate: acrefoot/day, say.
- jonknee 11y agoAcre feet is how water is sold and talked about in agriculture.
- duskwuff 11y agoThey're especially useful in agriculture because rainfall, and crop water consumption, are typically measured in inches of water. (Which is really a kind of "cubic inches (of water) per square inch (of land)", but the units cancel out.) So if you know the net water requirements of some crop given the climate, and you know how many acres of land you intend to grow it on, acre-feet are a natural, easy-to-calculate unit to measure the water supply needed.
- sampo 11y agoYou also need to know that 1 foot (30.48 cm) is 12 inces (2.54 cm).
- jonknee 11y agoWhich everyone reading the New Yorker surely does.
- freehunter 11y agoWhich everyone in the US knows. Even very uneducated people.
- sampo 11y agoI am from Europe, educated (PhD, if it matters), and I had to look it up. That's why I left the comment, to help others.
- freehunter 11y agoNo offense, but it's an article in the New Yorker about an issue in California. Your comment makes about as much sense as if you had said "yeah but you need to know that California is a state in the US". Europeans might not know it, but the target audience of the article certainly does. It's not exactly an extra bit of knowledge you need to learn, it's something you already know.
- beamatronic 11y ago> but when does the average person deal with acre-feet When villifying almond farms for their water usage
- bwy 11y agoI'm probably just ignorant, but I don't know too much about power (Is my light bulb usually around 80 W-h? 200W? 100kWh? I have no idea.) I think you're right, but I do also think the main point was the relative expenditure, a 30% increase.
- sp332 11y agoIncandescent bulbs are usually 60W but can be 40W for a reading lamp or 100W to light up a whole room. Those haven't been sold in most countries for a while now due to their extreme inefficiency, but other bulb types are often compared to a similar incandescent bulb. For example a 14W fluorescent bulb might say "60W equivalent". Watt-hours really are as simple as they sound. A 14W bulb that's on for an hour used 14 Watt-hours.
- deleted 11y ago[deleted]
- mtviewdave 11y ago>when does the average person deal with acre-feet? An acre-foot of water is approximately the amount of water that a suburban household uses in one year, which is why that unit is used when talking about non-agricultural water usage.
- ChuckMcM 11y agoIts also silly, since it takes zero kilowatts to pump water from San Diego to San Diego and if you're desalinating you have to realize that California is all coast line on the left hand side.